Some things from "gamerules.pzdat" explanation

[Musketeer]

Hey guys, what is this - I know English but what are these representing, why they were set or used in first place by developers as they are etc. Anything I should know?:

Thx!

LowAltitudeAttackPenalty 0
CloseTerrainDefenseBonus 0

[Yrfin]

Low altitude attack: if a fighter or tac bomber unit attacks a ground target, its ground defense is lowered by 5 points during that combat

Units in close terrain receive a +4 air defense bonus when attacked by air units

For more information
http://www.slitherine.com/forum/viewtopic.php?t=62845

[Musketeer]

Just finished reading of it, thanks!

[Molve]

To be clear, that other thread doesn't specifically discuss "gamerules.pzdat". That is, it presents the actual numbers in great detail, but not how and where they are stored (and thus, not how you change them if that's what you want to do).

For instance, the two example parameters of this thread, should probably read

LowAltitudeAttackPenalty -5
CloseTerrainDefenseBonus 4

...except one thing: I see the former but not the latter - there's no "CloseTerrainDefenseBonus".

Could it be that this "4" used to be hardcoded, but in a later version was made a changable parameter, and I'm just seeing an old version?